prohibited relation

no they got married 4 days back against will of my parents.. n that fellow took divorce from his first marriage claiming that he is impotent..

First of all the marriage whether null and void it's up to the parties to marriage to challenge it not outsider, your sister's marriage is up to her to go with it or not or challenge it's validity in the court, you have no legal right to challenge it. Secondly, the person was already married and got divorced before he married your sister, if he got divorced, was it through decree of competent court or not. Thirdly, the exact relationship between the parties to marriage has not been mentioned, the father's cousin's daughter doesn't make any sense it should be clearly mentioned in which manner they are related and according to which form of marriage was solemnized and what all ceremonies performed for the marriage. You come out here in this forum seeking free of cost legal advice from experts and not even providing correct and complete facts of the case.

ok he is my fathers cousin... groom's mother and my fathers mother are own sisters..

they eloped we dnt no where they are..they just sent an SMS saying they got married n switched of their phones...

Its a one sort of uncle and niece marrying each other is in sapinda and prohibited in North India.  You may challenge.

I fully agree with advise of expert Mr. Vijay Raj Mahajan.

1. You have no locus standie to interfer in the marriage of two adults, whether he/ she is your sister/borther.

2. No mention is there qua divorce of groom before solemnisation of his marriage.

3. The relation stated in the query is vague; otherwise, prohibited in Hindu Marriage Act, 1956.

ok IL come from the beginning..
.1) my sister eloped n got married on 10th of October.. we dnt no where they are and where they got married they just sent an SMS saying they got married and they switched of their phone's..
2) the person whom she got married is my fathers mothers own sisters son.. ( my fathers maasi son)
3)he is a divorce..from his first marriage.. which was an arranged marriage.. legally they took divorce..
will this marriage come under prohibited relation.. do I or my parents have legal rights to challenge this marriage..